The photo shows the probe with the cover removed.
-
In the center, there are no coils.
-
At the top, you see the Pulsed Field Gradient Coil (with the current leads desoldered). Looking closely at the coil, it's easy to see how passing current through it creates a linear field gradient.
-
Coils become more densly wound as you move up & down, which creates a stronger B(z) field as the windings get closer together.
-
Direction of windings is reversed above center vs. below center.
-
The coils you can see aren't actually the coils that create the field gradient over the sample, rather these are the active shielding coils that effectively insulate the main magnet field from the field of the gradient coil.
-
The real gradient coils are behind a Kel-F polymer insulator.